1. Field of the Invention
The present invention relates to a governor valve for a hydraulic controller in an automatic transmission.
2. Description of the Prior Art
A conventional governor valve 100, shown in FIGS. 4 and 5, comprises an adapter sleeve 120 having a line pressure supply bore 121 and a governor pressure output bore 122 made therein, a cylindrical governor rotary shaft 130 having a line pressure supply port 132 including notches intersecting the axis at right angles, a governor pressure output port 133 and a drain port 134, a centrifugal weight 140 mounted on one end 134a of the governor rotary shaft 130 and having a spring 141, and a spool 150 adapted to slide within the governor rotary shaft 130 with the weight 140 being urged against one end 151 thereof. In this governor valve, the weight 140 is operated to be opened or closed in accordance with a force due to rotation. Such opening or closing operation causes the spool 150 to slide correspondingly to control the governor pressure depending on the degree of communication of the governor pressure control chamber 152 with the line pressure supply port 132 and the drain port 134, thus supplying the governor pressure through the governor pressure output port 133.
In the governor valve 100 shown in FIGS. 4 and 5, however, dust and dirt in the fluid entering the line pressure supply port 132 of the governor rotary shaft 130 and causing a failure in operation of the governor valve 100 (valve sticking) is apt to collect around the inner peripheral portion 124 of the adapter sleeve 120 under the influence of the centrifugal action when the governor rotary shaft 130 is being rotated. Therefore, if a line pressure oil is fouled, the dust or dirt is difficult to move toward the governor pressure output port 133 and the drain port 134 under the influence of the centrifugal action (the separation of the line pressure oil of different specific weights and the dust contained in the line pressure oil by the centrifugal force). For this reason, the dust in the inner peripheral portion 124 of the adapter sleeve 120 and in the governor pressure control chamber 152 tends to increase in concentration and consequently, such dust is apt to enter into the clearance a between the adapter sleeve 120 and the governor rotary shaft 130, as well as the clearance between the rotary shaft 130 and the spool 150, thus causing the governor valve 100 to become stuck.